Preparation (MECHANISM: REDUCTION/N.SUB) and Base Properties

Question 1

Show the 4 mechanisms of halogenoalkanes to primary, secondary, tertiary and quaternary ion amine.

Answer 1

reagents: alcoholic NH3
conditions: heat, under pressure

Question 2

What is the mechanism for nitrobenzene to phenylamine?

Answer 2

mechanism: reduction

reagents: H2
conditions:Sn and HCl

used in the manufacturing of dyes.

Question 3

Explain the difference in base strength in terms of the availability of the lone pair of electrons on the N atom.

Answer 3

aromatic amines > ammonia > primary > secondary > tertiary > quaternary ion amine

In aromatic amines:
- benzene is an ELECTRON WITHDRAWING GROUP so it PULLS ELECTRONS AWAY FROM NITROGEN and into the ring structure
- therefore electron density at nitrogen is REDUCED so lone pair availability is reduced.

In the others:
- alkyl groups are ELECTRON PUSHING GROUPS so it PUSHS ELECTRONS TOWARDS NITROGEN.
- electron density at nitrogen INCREASES so lone pair availability is increased.